Denim Fabric Including Recycled Material

ABSTRACT

Denim fabric, suitable for use as apparel, and garments made therefrom, wherein the denim fabric is made from at least about 50 wt % fibers produced from post-consumer recycled polyester and recycled cotton. In particular, warp yarns are made of recycled cotton and the other cotton, and the filling yarns are made of the post-consumer recycled polyester and spandex material. The warp yarn may be plied with like reclaimed warp yarn, and/or with virgin fiber warp yarn. The warp and filling yarns are combined to make the denim fabric. The denim fabric produced has strength and related properties sufficient for consumer use. The fabric or garment may also be subjected to washing, handwork, and/or other finishing effects that would change the look and feel of the fabric or add special characteristics.

BACKGROUND

This invention is directed to denim fabrics including recycled materials including recycled cotton and recycled polyester.

Denim fabrics in the form of blue jeans and many other forms of apparel are very well known, perhaps due in part to denim being generally defined as a strong, serviceable, yarn-dyed cotton fabric.

It may be advantageous for the textile industry to reclaim and reuse resources, such as cotton scrap and post-consumer cotton, for making denim fabric, and to also look to using other recyclable materials, such as polyester and/or recycled polyester. Sources of recycled polyester may include the conversion of plastic bottles or other items made of polyester into fiber for textiles as a substitute for virgin polyester.

Accordingly, there is a need for denim fabric that is made of recycled materials, including recycled cotton and recycled polyester.

SUMMARY OF THE INVENTION

It is an object of the present invention to make apparel-quality denim fabric (and apparel therefrom) including at least about 50 wt % of recycled polyester and recycled cotton. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.

According to the present invention, denim fabrics can be produced containing from about 25 wt % to about 40 wt % of the denim fabric of post-consumer recycled polyester, which may be reclaimed from sources such as plastic soda or water bottles or other plastic items; and from about 25 wt % to about 40 wt % of the denim fabric of reclaimed cotton from sources such as pre-consumer waste and/or post-consumer waste, including denim waste; and from about 25 wt % to about 40 wt % of the denim fabric of other cotton; and up to about 3 wt % of the denim fabric of spandex.

Another embodiment of the present invention includes denim fabrics produced from warp yarn comprising recycled cotton and other cotton, and filling or weft yarn comprising recycled polyester and spandex, wherein the recycled cotton is from about 25 wt % to about 40 wt % of the denim fabric; the recycled polyester is from about 25% to about 40 wt % of the denim fabric; and the spandex is up to about 3 wt % of the denim fabric.

Another embodiment of the present invention includes a process to make denim fabric comprising the steps of (a) preparing a mixture of recycled cotton and other cotton into a warp yarn; (b) mixing the warp yarn with dyes and chemicals; (c) preparing a mixture of recycled polyester and spandex into a filling yarn; and (d) weaving the denim fabric from the warp and filling yarn of (b) and the filling yarn of (c).

Another embodiment of the present invention includes denim fabric constructed using warp yarns comprising a mix of recycled cotton and other cotton, with such warp yarns having been dyed using significantly reduced amounts of dyes and chemical, i.e., between about a 10% to 20% reduction compared to conventional dyeing methods, and a concomitant reduction in chemical usage. This may be permitted, due to use of pre-reduced indigo dyestuffs, which could, accordingly, lead to less usage of key chemicals, such as sodium hydrosulfite and sodium hydroxide. The environmental impact of production of the fabric may be further reduced, due to the use of pre-reduced indigo significantly reducing the amount of wastewater generated from the dyeing process. The fabric's filling yarns could comprise recycled polyester and spandex material, and the warp and filling yarns may be woven together in a conventional manner. More specifically, the warp yarn may be dyed with minimal overflow as compared to traditional denim dyeing methods, potentially resulting in about 15% less dyes and chemicals being needed for the process. Furthermore, a sulfur dye bath, which may be used in the final dyeing stage, may be recovered for re-use in dyeing of other fabrics.

Numerous other features and advantages of the present invention will appear from the following description.

DEFINITIONS

It should be noted that, when employed in the present disclosure, the terms “comprises,” “comprising,” and other derivatives from the root term “comprise” are intended to be open-ended terms that specify the presence of any stated features, elements, integers, steps, or components, and are not intended to preclude the presence or addition of one or more other features, elements, integers, steps, components, or groups thereof.

As used herein, the term “about” modifying the quantity of an ingredient in the compositions of the invention or employed in the methods of the invention refers to variation in the numerical quantity that may occur. The term about also encompasses amounts that differ due to different equilibrium conditions for a composition resulting from a particular initial mixture. Whether or not modified by the term “about,” the claims include equivalents to the quantities.

The term “filling yarn” or “filling” as used herein refers to yarns adapted for use as the filling or weft in fabric, which may be finer and have fewer turns of twist per inch than warp yarn. The filling yarn is generally woven widthwise or crosswise in fabric.

The term “warp yarn” or “warp” as used herein refers to yarns adapted for use as the warp in fabric, and may be stronger and have a higher number of turns of twist per inch than filling yarn. The warp yarn is generally woven lengthwise in fabric.

The term “cotton” as used herein refers to the fibrous substance composed of the fibers surrounding the seeds of various erect freely branching plants of the mallow family.

The term “manufactured fiber” as used herein refers to any filament or staple fiber derived by a process of manufacture from any substance which, at any point in the manufacturing process, is not a fiber.

The term “polyester” as used herein refers to a manufactured filament or staple fiber in which the fiber forming substance is any long-chain synthetic polymer composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not restricted to substituted terephthalic units, p(—R—O—CO—C₆H₄—CO—O-)_(x) and parasubstituted hydroxy-benzoate units, p(—R—O—CO—C₆H₄—O—)_(x).

The term “spandex” as used herein is a manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer comprised of at least 85 wt % of segmented polyurethane.

The term “post-consumer materials” or “post-consumer products” as used herein refers to materials or finished products which have served its intended use and has been diverted or recovered from waste destined for disposal.

The term “pre-consumer denim waste” or “post-industrial denim waste” as used herein refers to means cutting table scraps of denim cotton fabrics, natural cotton thread, cotton fiber waste, denim yarn waste, and denim fabric scraps left over from the cutting out of patterns for garments.

The term “% by weight” or “% wt” or “wt %” as used herein and referring to components of the denim fabric as a % of the total weigh of the denim fabric, unless otherwise specified herein.

These terms may be defined with additional language in the remaining portions of the specification.

DETAILED DESCRIPTION

While typical aspects of embodiment and/or embodiments have been set forth for the purpose of illustration, this Detailed Description and the accompanying drawings should not be deemed to be a limitation on the scope of the invention. Accordingly, various modifications, adaptations, and alternatives may occur to one skilled in the art without departing from the spirit and scope of the present invention. By way of a hypothetical illustrative example, a disclosure in this specification of a range of from 1 to 5 shall be considered to support claims to any of the following ranges: 1-5; 1-4; 1-3; 1-2; 2-5; 2-4; 2-3; 3-5; 3-4; and 4-5.

The present invention is directed to a denim fabric including at least about 50 wt % of recycled polyester and recycled cotton. In another embodiment, the present invention is directed to denim fabrics which can be produced containing from about 25 wt % to about 40 wt % of the denim fabric of post consumer recycled polyester, which may be reclaimed from sources such as polyester soda or water bottles or other plastic items; and from about 25 wt % to about 40 wt % of the denim fabric of reclaimed cotton from sources such as pre-consumer waste and/or post-consumer waste, including denim waste; and from about 25 wt % to about 40 wt % of the denim fabric of other cotton; and up to about 3 wt % of the denim fabric of spandex.

Another embodiment of the present invention includes denim fabrics produced from warp yarn comprising recycled cotton and other cotton, and filling yarn comprising recycled polyester and spandex, wherein the recycled cotton is from about 25% to about 40 wt % of the denim fabric; the recycled polyester is from about 25 wt % to about 40 wt % of the denim fabric; and the spandex is up to about 3 wt % of the denim fabric.

Another embodiment of the present invention includes a process to make the denim fabric comprising the steps of (a) preparing a mixture of recycled cotton and other cotton into a warp yarn; (b) mixing the warp yarn with dyes and chemicals; (c) preparing a mixture of recycled polyester and spandex into a filling yarn; and (d) preparing the denim yarn from the warp yarn of (b) and the filling yarn of (c).

As set forth above, denim fabric is comprised of a warp yarn and a filling yarn. The warp is produced from fibers which are dyed, usually indigo. The filling, or weft, is produced from fibers, usually natural-colored. The warp and the filling are woven together in such a way that the warp and the filling yarns are interlaced with the warp running length-wise and the filling running cross-wise. The selection of fibers for the warp and filling yarns affects the denim fabric's characteristics such as hand, elasticity, thickness, and twill.

The fibers for the production of the warp yarn and filling yarn can be from various sources. For example, the filling element yarn may be comprised of, but not limited to, polyester, polyester and cotton, cotton, cotton and spandex, or polyester and spandex. The element yarn may be comprised of, but not limited to, polyester, polyester and cotton, cotton, cotton and spandex or polyester and spandex. The warp or filling yarn may incorporate an elastic component to allow a degree of “give” in the fabric and any garments created therefrom. Stretch yarns produced by false twisting and heat setting or any other known texturing techniques are also known to those having ordinary skill in the art. In one preferred embodiment of the present invention, the filling yarns may comprise a blend of polyester and other fibers. The filling yarn is may be comprised of polyester and spandex. The warp yarn may comprise cotton.

The polyester, spandex and cotton fibers used in one embodiment of a product of the present invention may include warp yarn and the filling yarn coming from various sources such as, but not limited to, recycled post-consumer products, recycled post-industrial waste, or virgin fibers. The polyester may comprise up to 100 wt % recycled polyester, including up to about 25 wt %, or up to about 35 wt %, or up to about 40 wt %, or up to about 50 wt %, or up to about 60 wt % of recycled polyester in various embodiments of the present invention, where the polyester is recycled from post-consumer polyester products, post-industrial polyester waste, or a combination of both.

The cotton may comprise up to 100 wt % recycled cotton, including up to about 25 wt %, or up to about 35 wt %, or up to about 40 wt %, or up to about 50 wt %, or up to about 60 wt % of recycled cotton in various embodiments of the present invention, where the cotton is recycled from post-consumer cotton products such as clothing, post-industrial cotton waste such as waste fiber and yarn produced during yarn manufacturing or waste denim fabric produced during denim fabric or garment production, or a combination of any of the above.

The term “pre-consumer denim waste” or “post-industrial denim waste” may include cutting table scraps of denim cotton fabrics, natural cotton thread, cotton fiber waste, denim yarn waste, and denim fabric scraps left over from the cutting out of patterns for garments. While the collection and use of only pre-consumer denim waste is the simplest manner of practicing the present invention, optionally, according to the present invention, post-consumer denim waste may also be collected for utilization, along with, or instead of, the pre-consumer denim waste. If post-consumer denim waste, such as from old clothes repositories, rag companies, or the like, is collected, it may be desirable to remove all the non-denim materials therefrom. In particular, zippers, buttons, rivets, leather patches, synthetic fiber/non-wovens, or other foreign materials should be removed before the denim waste is utilized, and such removal may need to be accomplished by hand to ensure a raw material of sufficient integrity.

In one embodiment of the present invention, after collection of the denim waste, such waste may be sorted by color, either automatically using an optical sorter, or by hand. The two most common colors are indigo dyed (blue) and sulfur dyed black denim, although white, natural, red, green and other colors may also be used. After separation by color, the different color streams may be processed separately.

An optional first step after color sorting is a treatment to remove starch and sizing. This may be accomplished utilizing an amylase enzyme which converts starch on the yarn or fabric to sugar, which is water soluble and can be washed out of the fabric or the yarn. Such a treatment may be about 15 minutes long, and may be effectively practiced by adding 1-2% on weight of scraps of RAPIDASE-XL, a trademark for amylase enzyme manufactured by International Bio Synthetics, at 140° F. This enzyme treatment may be at about 140° F. and may be followed by a rinse bath for about five minutes at about 140° F. which extracts the sugar, and then by tumble drying. The equipment utilized to practice this treatment is typically commercial type washing and drying machines. A batch process may be desirable, since it utilizes conventional machines, but a continuous process can also be designed. Alternatively, the optional treatment could be practiced by acid hydrolysis.

The denim waste may be subjected to garneting, which is a process by which materials such as threads, rags, woven cloth scraps, and the like are broken up and returned to a fluffy, fibrous condition, simulating the original condition of the cotton fiber. This may be accomplished by first chopping the denim waste into smaller pieces (e.g. 2-6 inch maximum dimension), and then running it through a series of high speed cylinders. The cylinders are typically covered by carding-type wire, steel spikes, or the like. Garnetting breaks down the denim waste into individual cotton fibers. While any fiber length greater than about 0.4 inches is useful, garnetting rarely produces fibers having a length of greater than one and one-eighth inches. Lengths of about 0.4-0.8 inches are typical, with a length of about 0.6 inches (i.e. over 0.5 inches) being about average, and the vast majority (e.g. more than 90%) over 0.4 inches in length.

The recycled cotton may include waste fiber and waste yarn from the manufacturing process. In addition, recycled cotton may include cotton fibers recovered from garneting operations, where soft yarn (yarn that has not been coated with sizing material) that is waste from spinning and dyeing operations is cut and chopped back into fiber form.

Denim fabric produced according to the present invention may comprise from about 25 wt % to about 40 wt %, or from about 30 wt % to about 35 wt %, of post-consumer recycled polyester; and from about 25 wt % to about 40 wt %; or from about 30 wt % to about 35 wt %, of recycled cotton; and from about 25 wt % to about 40 wt %; or from about 30 wt % to about 35 wt %, of other cotton based.

The denim fabric may further comprise up to about 3 wt % of the denim fabric of spandex; or from about 0.5 wt % to about 2.5 wt % of spandex. The denim fabric may comprise at least about 50% of the total fiber content thereof of post-consumer recycled polyester and recycled cotton and may comprise up to about 80% of the total fiber content thereof of post-consumer recycled polyester and recycled cotton.

The dying of the warp usually consists of many dying processes where the warp fibers are dipped into indigo blue dyes until the desired warp color is obtained. The filling fibers are usually not dyed, but may be dyed using the same process. It is the weaving together of these two elements—the indigo blue warp and the white or natural filling—that creates the distinctive blue top and white back denim effect. The fabric or garment created from the warp and filling elements may also be dyed by passing the fabric or garment through a hot dye solution. The fabric or garment may also be subjected to washing which includes chemical lotions, machine washing such as stone washing, and/or handwork. The fabric or garment may also be subjected to other finishing effects that would change the look and feel of the fabric or add special characteristics such as, but not limited to, durable press, water repellency, flame resistance, and/or shrinkage control.

It will thus be seen according to the present invention a denim fabric, garments being made from same, and/or a woven fabric having filling and/or warp yarns, wherein the warp yarn comprises recycled cotton and other cotton and the filling yarn comprises post-consumer recycled polyester and spandex wherein the denim fabric comprises from about 50 to about 80 wt % of recycled polyester and recycled cotton, and advantageous methods of producing such denim fabric.

In one preferred embodiment of the present invention, denim fabric could be constructed using warp yarns comprising a mix of recycled cotton and the other cotton, with such cotton preferably having been dyed using significantly reduced amounts of dyes and chemicals. The significant reduction in dye, i.e., between about a 10 to 20% reduction compared to conventional dyeing methods, and a concomitant reduction in chemical usage, may be due to the use of pre-reduced indigo dyestuffs, which could, accordingly, lead to less usage of key chemicals, such as sodium hydrosulfite and sodium hydroxide. The environmental impact of production of the fabric may be further reduced, because use of pre-reduced indigo could significantly reduce the amount of wastewater generated from the dyeing process.

More specifically, the warp yarn could be dyed with minimal overflow as compared to traditional denim dyeing methods, potentially resulting in about 15% less dyes and chemicals being needed for the process. Furthermore, a sulfur dye bath, which may be used in the final dyeing stage, may be recovered for re-use in dyeing of other fabrics. Such dyeing process would potentially generate lower volume and lower strength wastewater than with traditional denim dyeing methods.

For purposes of illustration, a process for the dyeing of cotton fibers may comprise the steps of:

-   -   a) preparing an aqueous solution comprising pre-reduced indigo         and a reducing agent;     -   b) introducing cotton fibers to said aqueous solution;     -   c) removing said cotton fibers from said aqueous solution;     -   d) allowing oxidation to occur;     -   e) reintroducing said oxidized cotton fibers to said aqueous         solution;     -   f) repeating steps c), d) and e) until desired shade of indigo         is reached; and     -   g) introducing said oxidized cotton fibers to a second aqueous         solution comprising sulfur dye.

In addition to the foregoing steps for dyeing cotton fibers, the process may further include the steps of:

-   -   h) removing said cotton fibers from said aqueous solution;     -   i) allowing oxidation to occur;     -   j) reintroducing said oxidized cotton fibers to said second         aqueous solution; and     -   k) repeating steps h), i) and j) until desired shade is reached.

The foregoing process may be used for dyeing of fibers, fabric or both, and the process from about 10 to about 20% less dye than conventional dyeing methods.

The fabric's filling yarns could comprise recycled polyester and spandex material, and the warp and filling yarns can be woven together in a conventional manner. In one embodiment of the present invention, the fabric would be woven with filling yarn consisting of polyester filament wrapped around a spandex core, where the polyester has at least 80% post-consumer recycled content.

While the invention has been herein shown and described in what is presently conceived to be the most practical and preferred embodiment thereof, it will be apparent to those of ordinary skill in the art that many modifications may be made thereof within the scope of the invention, which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent products and methods. 

What is claimed is:
 1. A denim fabric comprising: a) from about 25 wt % to about 40 wt % based on the denim fabric of post-consumer recycled polyester, b) from about 25 wt % to about 40 wt % based on the denim fabric of recycled cotton, c) from about 25 wt % to about 40 wt % based on the denim fabric of other cotton, and d) up to about 3 wt % based on the denim fabric of spandex.
 2. The denim fabric of claim 1 comprising about 30% to about 35 wt % based on the denim fabric of post-consumer recycled polyester.
 3. The denim fabric of claim 1 comprising about 30 wt % to about 35 wt % based on the denim fabric of recycled cotton.
 4. The denim fabric of claim 1 comprising about 30 wt % to about 35 wt % based on the denim fabric of other cotton.
 5. The denim fabric of claim 1 wherein the post-consumer polyester is a filament or staple fiber derived from plastic soda or water containers.
 6. The denim fabric of claim 1 wherein the recycled cotton of b) is pre-consumer cotton waste.
 7. The denim fabric of claim 1 wherein the recycled cotton of b) is pre-consumer denim waste.
 8. A process to make the denim fabric comprising the steps of: a) preparing a mixture of recycled cotton and other cotton into a warp yarn; b) mixing the warp yarn with dyes and chemicals; c) preparing a mixture of recycled polyester and spandex into a filling yarn; and d) preparing the denim yarn from the warp yarn of (b) and the filling yarn of (c).
 9. A process as recited in claim 8 wherein step (a) is practiced so as to produce denim fibers with an average length of about 0.6 inches, so that the denim fabric has denim waste fibers with an average length of about 0.6 inches.
 10. A process as recited in claim 8 wherein step (a) includes collecting waste fiber and waste yarn.
 11. A process as recited in claim 8 wherein step (a) includes collecting pre-consumer waste fiber and waste yarn.
 12. A process as recited in claim 8 wherein step (a) includes collecting pre-consumer fabric waste.
 13. A process as recited in claim 8 wherein step (a) includes collecting post consumer denim waste.
 14. A denim garment produced from denim fabric, the denim fabric comprising: a) from about 25 wt % to about 40 wt % based on the denim fabric of post-consumer recycled polyester, b) from about 25 wt % to about 40 wt % based on the denim fabric of recycled cotton, c) from about 25 wt % to about 40 wt % based on the denim fabric of other cotton, and d) up to about 3% based on the denim fabric of spandex.
 15. A process for dyeing warp yarn of a denim fabric comprising the steps of: a) dyeing the warp yarn with minimum overflow as compared to traditional denim dyeing methods; b) introducing said warp yarn to an aqueous solution comprising sulfur dye; c) recovering the aqueous solution bath comprising sulfur dye in the form of recovered sulfur dye bath; and d) re-using the recovered sulfur dye bath in dyeing of other fabrics. 